Such a process is known from French patent FR-B-2 497 234 (equivalent U.S. Pat. No. 4,363,722), which is applied to wastes from the machining of titanium that have been pre-treated by pneumatic and magnetic separations, in order to detect any suspiciously high density inclusions therein. The wastes can be moved along in a continuous stream, with the X-rays passing through this stream and being detected by a sensor whose output signal is interpreted by a computer. Each part of the stream that contains a suspicious object that has been detected in this way is automatically removed and discarded. The accepted wastes may contain particles of high density material, for example tungsten carbide (hereinafter WC) WC, that are smaller than 0.38 mm or another specified value.
In the practice, globules of WC with a diameter of less than 0.38 mm and randomly cast into the X-rayed field are used as defect-measuring standards. The inventors determined that their detection was irregular and uncertain, and that the wastes accepted by the inspection process would contain, in places, inclusions that were "unacceptable" in principle, that is of high density and larger than 0.38 mm.
The inventors have taken on the task of improving the reliability, and if possible the sensitivity, of this X-ray inspection.